Inorganic Chemistry - Chemical Tests

Question 1

what is the test for hydrogen?

Answer 1

use a lit splint, if gas is present the gas will pop

Question 2

what is the test for oxygen?

Answer 2

use a glowing splint, if gas is present the splint will relight

Question 3

what is the test for carbon dioxide?

Answer 3

bubble the gas through limewater, if gas is present limewater turns cloudy

Question 4

what is the test for ammonia?

Answer 4

use red litmus paper, if gas is present litmus paper will turn blue

Question 5

what is the test for chlorine?

Answer 5

use damp litmus paper, if gas is present litmus paper turns white (bleached)

Question 6

how do you carry out a flame test?

Answer 6

• a platinum or nichrome wire (inert, high melting point) is dipped into concentrated hydrochloric acid to remove impurities
• the wire is dipped into the salt being tested so some salt sticks to the end
• the wire and salt are held in a non-luminous (roaring) bunsen burner flame
• the colour is observed

Question 7

what colour is lithium in a flame test?

Answer 7

red

Question 8

what colour is sodium in a flame test?

Answer 8

yellow

Question 9

what colour is potassium in a flame test?

Answer 9

lilac

Question 10

what colour is calcium in a flame test?

Answer 10

orange-red

Question 11

what colour is copper (II) in a flame test?

Answer 11

blue-green

Question 12

what is the test for ammonia?

Answer 12

• add sodium hydroxide and warm
• if ammonium ions are present, ammonia gas will form
• this will turn damp red litmus paper blue

Question 13

what is the test for copper(II)?

Answer 13

• add sodium hydroxide
• a blue precipitate of copper hydroxide will form

Question 14

what is the test for iron(II)?

Answer 14

• add sodium hydroxide
• a green precipitate of iron(II) hydroxide will form

Question 15

what is the test for iron(III)?

Answer 15

• add sodium hydroxide
• a brown precipitate of iron(III) hydroxide will form

Question 16

how do you test for carbonate ions?

Answer 16

• add hydrochloric acid
• if carbonate ions are present, fizzing will occur
• test the gas for carbon dioxide using limewater

Question 17

how do you test for chloride ions?

Answer 17

• add nitric acid to remove impurities
• add silver nitrate solution
• if chloride is present then a white precipitate of silver chloride is formed

Question 18

how do you test for bromide ions?

Answer 18

• add nitric acid to remove impurities
• add silver nitrate solution
• if bromide is present then a cream precipitate of silver bromide is formed

Question 19

how do you test for iodide ions?

Answer 19

• add nitric acid to remove impurities
• add silver nitrate solution
• if iodide is present then a yellow precipitate of silver iodide is formed

Question 20

how do you test for sulfate ions?

Answer 20

• add hydrochloric acid to remove impurities
• add barium chloride
• if sulfate ions are present, a white precipitate of barium sulfate will form

Question 21

how do you test for the presence of water?

Answer 21

• add anhydrous copper (II) sulfate to a sample
• if water is present the anhydrous copper (II) sulfate will change from white to blue

Question 22

what is a physical test if water is pure?

Answer 22

if the sample is pure water it will boil at 100C